necking down after collecter?

The shop my Duster is in wants to neck down the exhaust from TCI headers to a 2 inch pipe. The collectors are 3", after the foot of 2" pipe they plan to use, the 2" extensions the headers came with, they plan on going to 3" out the back. Is this stupid or a good idea?

The shop my Duster is in wants to neck down the exhaust from TCI headers to a 2 inch pipe. The collectors are 3", after the foot of 2" pipe they plan to use, the 2" extensions the headers came with, they plan on going to 3" out the back. Is this stupid or a good idea?

One muffler shop dude told me (and it made sense) that the exhaust is hot near the headers and cools as it travels out the back. That's why you can hold your hand over the rear exhaust pipe but not at the header outlet (too hot). Cooling gas should condense.....so the same amount of exhaust gas (volume) at the header should decrease in volume by the amount that it cools (temp) off as it travels to the rear.

One muffler shop dude told me (and it made sense) that the exhaust is hot near the headers and cools as it travels out the back. That's why you can hold your hand over the rear exhaust pipe but not at the header outlet (too hot). Cooling gas should condense.....so the same amount of exhaust gas (volume) at the header should decrease in volume by the amount that it cools (temp) off as it travels to the rear.

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You're referring to what's called "tuned exhaust".... what you do.. is... you take shoe polish, and you wipe a fkn line every 8 inches from the collector on the extension.... or about 3 line...the last line of shoe polish that burns off.... is where you would attach the muffler....imo that has NOTHING to do with the diameter required...smaller would probably move that line further down the pipe even..'more heat'. Need to know what you're doing and not let some Ck biter steer you queer.

One muffler shop dude told me (and it made sense) that the exhaust is hot near the headers and cools as it travels out the back. That's why you can hold your hand over the rear exhaust pipe but not at the header outlet (too hot). Cooling gas should condense.....so the same amount of exhaust gas (volume) at the header should decrease in volume by the amount that it cools (temp) off as it travels to the rear.

Click to expand...

He was mentioning something like that, that the neck down needed to be where the paint no longer burned off the exhaust was his explanation. You did a much better job of it. I'm just concerned that it is not far enough back and too narrow. I posted the specs above for the engine. I have 3 step headers on it: 1-5/8 to 1-3/4 to 1-7/8 into a 3" collector.

Do you really mean they want to go straight to 2" and then later bump it back to 3"??

Stupid.

Except for maybe using a choke at or in the collector, the exhaust should continue at collector diameter for some length and terminate into very large volume in order to take advantage of any wave tuning the extension might help create.

He was mentioning something like that, that the neck down needed to be where the paint no longer burned off the exhaust was his explanation. You did a much better job of it. I'm just concerned that it is not far enough back and too narrow. I posted the specs above for the engine. I have 3 step headers on it: 1-5/8 to 1-3/4 to 1-7/8 into a 3" collector.

The shop my Duster is in wants to neck down the exhaust from TCI headers to a 2 inch pipe. The collectors are 3", after the foot of 2" pipe they plan to use, the 2" extensions the headers came with, they plan on going to 3" out the back. Is this stupid or a good idea?

Thanks

Click to expand...

Quick! Run away, very quickly. Run your ass off. There secretly anti MoPar as well as plain old fashion stupid.

Do you really mean they want to go straight to 2" and then later bump it back to 3"??

Stupid.

Except for maybe using a choke at or in the collector, the exhaust should continue at collector diameter for some length and terminate into very large volume in order to take advantage of any wave tuning the extension might help create.

You're referring to what's called "tuned exhaust".... what you do.. is... you take shoe polish, and you wipe a fkn line every 8 inches from the collector on the extension.... or about 3 line...the last line of shoe polish that burns off.... is where you would attach the muffler....imo that has NOTHING to do with the diameter required...smaller would probably move that line further down the pipe even..'more heat'. Need to know what you're doing and not let some Ck biter steer you queer.

You can also get 3" "reducers" made for a 3" collector that are made to weld the rest of your exhaust to. Either way works. The torsion bar cross member is typically pretty close though... So the longer extensions may be more trouble.